how much will an intake/exhaust hurt gas mileage?
 

Hi,

I was just wondering how much an exhaust (probably Fast intentions) would adversely affect my gas mileage?

Also, what if I pair it with the Stillen gen 3 Intake?

Would the Intake diminish my torque gains form the Exhaust?

Would my car be louder (don't really want it loud, just want better sound) with the Fast Intentions CBE with 18" resonators even if I DON"T put in HFCs?

It all depends on how you drive the car... if you keep your right foot out of it then it SHOULD improve your gas mileage for the simple fact that the engine can run more efficiently and doesn't need to use as much power to push all of that air through the car.

Obviously if you are flooring it at every stop light, it's going to use more power because it has more power.

On the exhaust being loud F.I. IMO is a good choice, but I haven't heard one in person so i'm not the best to ask. Is loud to you loud inside the car or outside? Everyone has a different definition of what loud is. Tony from F.I. is the guy to ask about that, but 18" resonators on stock cats shouldn't be very loud at all from what I have seen some people say on here. I went with the ART pipes which produce more power than HFC's but are not as loud. I am all stock aside from them though and am waiting for ARK's and Motordyne's new system before I make my final choice on a cat back.

On the torque loss with an intake... I don't think it would be much, if at all... most guys here use the G3's as they are proven power, but here again... Motordyne is going to be coming out with an intake over the next 6 months or more (guessing) and they make EXCELLENT products ... for me it's worth the wait.

I know this is an old thread but I wanted to add .02

Before exhaust 29 mpg. Now, with new exhaust (GTHAUS) I'm getting 31MPG (and Im driving it way harder).

Next mod. HFC's...ill let you know how that changes things..if it does.

Anything that frees up restrictions on the engine breathing (in or out) should only improve gas mileage. As long as you drive the same way you did before the mods, you should realize those benefits. If you're giving it more throttle than before, then obviously you will not see much (if any) improvement.

I bet hfcs/test pipes would really help. One of the many reasons bikes get better mileage is because cats aren't required for them.

they are on sport bikes now

As a general rule, more air ingested requires more fuel; thus, more power typically means worse gas mileage.

But here, we're talking about maybe 1 MPG worse at most. Possibly no significant change depending on how you drive.

The only way to get "free" power, is to reduce parasitic losses (e.g., lighter mass on rotating drivetrain components).

Another exception would be to run leaner under load (i.e., use less fuel), which, might result in more power, if the tune was running overly rich and quenching timed spark events (this car runs pretty rich up top from the factory).

Neither should result in any appreciable losses down low, both should gain mid and up top. A tune can mitigate all of this, of course.

But you are getting more power at lower RPMs, right? So I'm not sure how you get worse gas mileage. I also thought that it should improve. I can't tell yet as all I've added are K&N filters. Post MAF tubes are next.

It really varies on the brand of the intake and if it is a short ram or cold air and on what kind of car as well. But no matter what you will lose MPG for sure. It is funny how we would get call from people sometimes that would ask "how much MPG gain they wil get from installing X brand intake system?". Don't they know more HP = less MPG!